Purpose of the study: The authors present a prospective and mono-operator study of 91 gleno-humeral arthroscopies for post-traumatic antero-inferior instability of the shoulder. The aim of the study was to obtain a dynamic understanding of the relationship between the anatomic lesions to allow the integration of all the described lesions into literature and to produce a natural history of lesions in antero-inferior shoulder instability.
Materials: 91 endoscopies for post-traumatic instability of the shoulder were performed by the same surgeon. Revision chart comprised 67 purely descriptive items. For the purpose of the study, the patients were divided into 4 groups of dislocation (first dislocation: 9 cases, 1 to 2 recurrences: 12 cases; 3 to 5 recurrences: 23 cases; more than 5 recurrences: 32 cases) and 1 group of subluxation (15 cases).
Method: The statistical evaluation of each individual data item gathered value allowed the selection of the most significant lesions and to regroup them into "lesions families", relations to the same physiopathological mechanism (traumatic or degenerative). The correlation between each lesion in terms of evolution, age and number of recurrences was studied.
Results: The first and most constant lesion is the periosteal avulsion of the antero-inferior labrum ("single lesion": healing potential of +/- 30 per cent, in ectopic position in +/- 90 per cent). With recurrences, the avulsion of the gleno-humeral ligament adds this "single lesion" ("double lesion". Healing potential of +/- 50 per cent, in ectopic position in +/- 90 per cent). Continuing the recurrence, we also noted a degenerative and plastic deformation under the level of the glenoid rim ("triple lesion": infra-glenoid degenerescence) then over the glenoid rim ("quadruple lesion": supra glenoid degenerescence). The age factor and duration of evolution were not negligible and one must associate the "labro-ligament complex" studies with the avulsion lesions of the long head of the biceps (SLAP lesions) in which the frequency varies from 15 per cent to 30 per cent and which was consistently present in patients above 35 years of age.
Discussion: The authors believe that recurrences give rise to a progressive worsening of the lesions by the sum of the separate lesions. They propose a physiopathological classification in 4 stages where each lesions has its own healing potential, which explains the apparent large variation in endoscopic aspects of antero-inferior shoulder instability.
Conclusion: This classification should permit a precise therapeutic strategy in post-traumatic anterior instability, according to the most recent techniques of endoscopic reattachment of the labro-ligament complex.